It appears I am in need of an EQ

She says there isn’t enough bass and the 20 year old in me gets that. However, I don’t want to change out the electronics or the speakers or add a subwoofer...

Impossible. You do realize this, I hope? Because otherwise put your gear on Craig’s List you're not worthy.

Does the 20 year old in you remember ever seeing a club with bass coming from two tiny little speakers? No? Didn’t think so. Maybe your wife? Ask her about it. She’s the one wants the sound. Your turn to be the man and explain. Then deliver. What she wants.

Steakster is right, you need more subs. Not just two, you need four. But they don’t have to be monsters, and if you are clever she doesn’t even have to see them.

What you need to know is with subs the prevailing dogma is all wrong. Size and power and EQ and "timing" and all the other blather is just that, blather. What works with bass is having more sources of bass.

So what you do is shop around for four (or more) small, affordable subs, preferably long tubes no more than 8" diameter or whatever you can fit behind furniture along the walls. Using four (or more) it does not hardly matter where they go. Using four (or more) it does not hardly matter how big or powerful they are. Using four (or more) its almost impossible to NOT get awesome, powerful, deep, articulate, clean, and tuneful bass that will perfectly integrate with your stereo pair that you love so much.

This is totally the way to go. Just don’t have to be boxes like these. Can be whatever shape, and they do not have to match. These don’t, and the bass is to die for!
https://systems.audiogon.com/systems/8367

Whatever you do, do NOT get EQ. If you get to the point where you can’t think of anything else and are all set and ready to EQ just do yourself a favor slice your wrists in the tub, consider it a mercy.

EQ might be better bass to you, but I don't know if your wife would really think so. EQ basically makes for only slightly deeper bass, but what I would think she might really be looking for is not that, but some git up and go, particularly as volume is increased. The real answer then might be more bass dynamics than manipulated tone. That would point more to steakster's solution. You likely can each have it your own way with that approach. The bad news of course, is that you need to spend a little more and have even more equipment in the room. 

I'm a married audiophile also. Your mission, should you choose to accept it: pitch the subwoofer scenario to your wife. And remember, if for any reason you are caught, I will disavow any knowledge of your actions. Good luck. This message will self destruct in 5 seconds. 

Um, do you need bass or do you need room treatment?

Good room treatment will make the bass tighter and fuller, especially if yo are starting from zero. This may be all you need, and your best option.

If you can, measuring your room and adjusting an EQ based on that really helps.

If you just want to dive right into EQ, strongly suggest the Schiit Loki, as the simplest solution, a miniDSP as your more advanced.

Best,

E